This book adopts a novel, even revolutionary, approach to healing a wide range of psychological problems in therapy. The premise is that all of us have a number of multiple personalities within us who powerfully influence every aspect of our lives. By locating these internal parts and neutralizing the effects of the high-energy, often traumatic, experiences that created them, Parts Psychology demonstrates that patients can heal rapidly and completely from long-held emotional issues.

The core of the book contains the healing narratives for 12 patients who, except for the problems that brought them to therapy, lead relatively normal lives. Several chapters describe the treatment process for such problems of emotional intimacy as lost love, low sexual desire, jealousy, and sexual swinging. Others describe issues of compulsion such as binge eating, porn addiction and bulimia. Several chapters detail success stories in the treatment of anger and rage, depression, grief and anxiety. Child abuse appears in the history of a number of patients. Each story begins with the first meeting with the therapist and concludes when the patient graduates from therapy.

A first look at patients' inner worlds might suggest to some the presence of multiple personality disorder (dissociative identity disorder). And many patients are shocked to find that they can have conversations with themselves. However, the case studies illustrate that having unconscious parts (subpersonalities), represented by a range of images, is normal. Although people may use fascinating images to represent their internal worlds, the more important content of a part of the self is its unique set of memories. Life experiences recorded in memory are the subject matter for therapy. Adult issues always have to do with the painful or novel life experiences that created the parts and the problems in a person's life, especially the adaptations and experiences of childhood.